Brake probs...jeez.

[jetdoc]

Hey everyone. 79 CBX. Never had brake probs until we moved last year and I left it in my shed during the winter, as the garage was full of boxes.



Brakes were locked up. Just now got around to working on it. I pulled off all three calipers, cleaned out real good and reassembled. I had one caliper that the inner seal need to be replaced but other than that they all seemed ok.



Got the back assembled, no probs, bled nice and is ok.



Now to the front. I am having major problems bleeding the front. It is very spongy and wont get tight. Plus on on one side the bleeder valve will seep fluid when I tighten it back up after pumping handle. I replaced it with the one on the rear caliper and it seems a bit better, but the brakes still will not get tight. It seems if I pump the handle with smaller pumps it helps a bit and will hold, I bleed it and release. Still very spongy.



Any help would be great. I've had my CBX since 82 and its a nice clean bike.

[Jeff Bennetts]

jetdoc, check the front master cylinder. make sure its free of particles and the return hole is not blocked. I would just take the M/C apart, inspect and clean it, the job is only 1/2 way done if you go through the front brake calipers and not the M/C too.



jb

[jetdoc]

Thanks Jeff I will try it. I ordered new bleeder screws for all three brakes. I tried to bleed again and had the same problem. Im not getting air bubbles from either of the two front calipers, so I can't figure out why its spongey.



I will take your advise sir and let you know what I come up with.



RonW

[Dave Ditner]

After you've pumped a bunch of fluid through it and gotten nothing but a spongy lever, try this: Put the bike on the side stand and turn the bars full left. Pull the brake lever all the way in and tie it there with a tie wrap. Walk away from it for a day. When you come back, take a plastic mallet or a wood block, and gently tap both calipers for a couple minutes each. Then shake the lines. Then remove the chicken band and lightly and partially stroke the brake lever. You should gain a lot of lever.

[jetdoc]

Thanks Dave. I rode it yesterday for a test ride. The rear brake is fine. The front ones seem to build up pressure if I pump the lever a few times then apply the brakes. On my test ride if I just applied the front brake like you're supposed to the lever will just go to the grip with no braking to speak of, but again, if I pump it a couple of times then it works fine.



I'll try your suggestion as you and Jeff gave me some good tips, you guys rock.

[Dave Ditner]

Sounds like air to me. Pay attention to the way you set the bike, on the sidestand and bars turned to the left. That points the connector pipe up toward the master.

[jetdoc]

Dave, I just want to let you know that I figured the procedures you were giving me was just some sort of snake oil fix. I want to go on record as saying I came home today, preceded to do the second part of what you advised. Do you know what happened? It worked just as you said!



YOU DA MAN Dave, . I really appreciate your tip my friend. I honestly thought to myself, "uh yea, that will work". I stand corrected and again, thanks.

[Dave Ditner]

Here's the way I think that works. First, the reason that it's so hard to bleed: The master cylinder has very limited capacity and it's really hard to get air bubbles to move with much limited fluid displacement. A help there is to remove one caliper from the system while you bleed the other. I do this by removing the line from the caliper and using a 3/8-24 bolt with a nylock self locking nut and two crush washers to seal it. Don't use a 3/8-16 (coarse thread) /b]because the fluid will leak through the threads. When you get one side done, switch the bolt and do the other. Then connect both and do the bleed normally. If the lever is still spongy, tie it back and walk away. What happens, I think, is when pressure is applied, the size of the air bubbles is greatly reduced and they can migrate upward slowly. Some do. Tapping the calipers and shaking the lines helps this if any should still be trapped.

Thanks for parts of this tip belongs to the Pope boys, Ray and Rick, and maybe even a bishop or two..

[Jeff Bennetts]

Old dogs can learn new tricks after all.



jb

[jetdoc]

Jeff, I've been a mech on airplanes since 1978 and I learn new tricks almost daily. BTW, I don't know if I told you but I did take the front M/C apart and clean it out as you suggested. It was totally cruddy and funked up, thanks.



I rode my baby today after work and she stops like nobodys business. I may not post much on this board but I do lurk and read. This is the best CBX board on earth, , so much knowledge here and more importantly there are guys willing to share their knowledge.

[Larry Zimmer]

Thought I'd bring this one up for all who might be doing some Winter brake work and having bleeding troubles. Thanks, Dave.

[cbx6ss]

I finally solved a similar problem on my '81 by replacing the original lines with stainless steel braided lines from CBXMAN. Made the front brakes solid as a rock!